Add system graph (wip)

include/Nazara/Core/Systems/SystemGraph.inl

@@ -0,0 +1,74 @@
+// Copyright (C) 2022 Jérôme "Lynix" Leclercq (lynix680@gmail.com)
+// This file is part of the "Nazara Engine - Core module"
+// For conditions of distribution and use, see copyright notice in Config.hpp
+
+#include <Nazara/Core/Systems/SystemGraph.hpp>
+#include <Nazara/Core/Error.hpp>
+#include <stdexcept>
+#include <Nazara/Core/Debug.hpp>
+
+namespace Nz
+{
+	namespace Detail
+	{
+		template<typename, typename = void>
+		struct SystemGraphAllowConcurrent : std::bool_constant<true> {};
+
+		template<typename T>
+		struct SystemGraphAllowConcurrent<T, std::void_t<decltype(T::AllowConcurrent)>> : std::bool_constant<T::AllowConcurrent> {};
+
+		template<typename, typename = void>
+		struct SystemGraphExecutionOrder : std::integral_constant<Int64, 0> {};
+
+		template<typename T>
+		struct SystemGraphExecutionOrder<T, std::void_t<decltype(T::ExecutionOrder)>> : std::integral_constant<Int64, T::ExecutionOrder> {};
+	}
+
+	template<typename T>
+	template<typename... Args>
+	SystemGraph::Node<T>::Node(Args&&... args) :
+	system(std::forward<Args>(args)...)
+	{
+	}
+
+	template<typename T>
+	void SystemGraph::Node<T>::Update(float elapsedTime)
+	{
+		system.Update(elapsedTime);
+	}
+
+	inline SystemGraph::SystemGraph(entt::registry& registry) :
+	m_registry(registry),
+	m_systemOrderUpdated(true)
+	{
+	}
+
+	template<typename T, typename... Args>
+	T& SystemGraph::AddSystem(Args&&... args)
+	{
+		NazaraAssert(m_systemToNodes.find(entt::type_hash<T>()) == m_systemToNodes.end(), "this system already exists");
+
+		auto nodePtr = std::make_unique<Node<T>>(m_registry, std::forward<Args>(args)...);
+		nodePtr->executionOrder = Detail::SystemGraphExecutionOrder<T>();
+
+		T& system = nodePtr->system;
+
+		m_nodes.emplace_back(std::move(nodePtr));
+		m_systemOrderUpdated = false;
+
+		return system;
+	}
+
+	template<typename T>
+	T& SystemGraph::GetSystem() const
+	{
+		auto it = m_systemToNodes.find(entt::type_hash<T>());
+		if (it == m_systemToNodes.end())
+			throw std::runtime_error("this system is not part of the graph");
+
+		auto& node = static_cast<Node<T>&>(*m_nodes[it->second]);
+		return node.system;
+	}
+}
+
+#include <Nazara/Core/DebugOff.hpp>